One-step multicomponent synthesis of chiral oxazolinyl-zinc complexes.

Background: Typically, oxazolinyl metal complexes are synthesized in two steps, where the free ligand is prepared by the condensation reaction between a functionalized nitrile and an amino alcohol in the presence of a Lewis or Brønsted acid catalyst, followed by a further reaction with metal salts to obtain the corresponding metal complexes. Very often, the yield afforded by the two-step procedure is not high, and very few oxazolinyl zinc complexes have been prepared by this route. Given that metal-oxazoline complexes often contain Lewis acidic metals, it is conceivable that the two steps may be telescoped.

Silver-catalysed enantioselective addition of O-H and N-H bonds to allenes: a new model for stereoselectivity based on noncovalent interactions.

The ability of silver complexes to catalyse the enantioselective addition of O-H and N-H bonds to allenes is demonstrated for the first time by using optically active anionic ligands that were derived from oxophosphorus(V) acids as the sources of chirality. The intramolecular addition of acids, alcohols, and amines to allenes can be achieved with up to 73% ee. The exploitation of a C-H anomeric effect allowed the absolute configuration of a sample of 2-substituted tetrahydrofuran of low ee to be unambiguously assigned by comparison of the chiroptical ORD and VCD measurements with calculated spectra.

In situ investigation of the oxidative addition in homogeneous Pd catalysts by synchronised time resolved UV-Vis/EXAFS.

Simultaneous structuro-kinetic information obtained via time resolved stopped-flow/UV-Vis spectroscopy/dispersive EXAFS (EDE) experiments elucidated a two-step process for the addition of iodobenzene to [(Ph3P)2Pd(dba)].

Multigram synthesis of well-defined extended bifunctional polyethylene glycol (PEG) chains.

A series of novel, well-defined, unsymmetrical poly(ethylene glycol) chains of the type X(OCH(2)CH(2))(n)()Y (where X = protecting group; Y = nucleofuge or a different protecting group; n = 3, 6, 9, 12, 15, 18, and 24) were prepared in high yields by applying orthogonal protecting groups. The purity of the compounds was fully verified by elemental and high-resolution mass spectrometry analyses.

Phosphorus-nitrogen-phosphorus ligands: cooperative effects between nitrogen and phosphorus substituents on catalytic activity.

A new generation of PNP compounds bearing different diarylphosphine groups were prepared and used as ligands in palladium-catalysed Suzuki cross-coupling reactions. Rates of oxidative addition of iodobenzene to (PNP)Pd[0] complexes were measured using UV spectroscopy. Synergistic effects between the N- and P- substituents were identified and correlated in redox and catalytic chemistry.

Dicationic [(BINAP)Pd(solvent)2]2+[TfO-]2: enantioselective hydroamination catalyst for alkenoyl-N-oxazolidinones.

Dicationic (BINAP)palladium(II) complex induced high enantioselectiviies in the addition of primary (and secondary) aromatic amines to alpha,beta-unsaturated oxazolidinones (up to 93% ee).